Instrument control

Instrument control consists of connecting a desktop instrument to a computer and taking measurements.

History

In the late 1960s the first bus used for communication was developed by Hewlett-Packard and was called HP-IB (Hewlett-Packard Interface Bus). Since HP-IB was originally designed to only work with HP instruments, the need arose for a standard, high-speed interface for communication between instruments and controllers from a variety of vendors. This need was addressed in 1975 by the Institute of Electrical and Electronic Engineers (IEEE) published ANSI/IEEE Standard 488-1975, IEEE Standard Digital Interface for Programmable Instrumentation, which contained the electrical, mechanical, and functional specifications of an interfacing system. This bus is known by three different names, General Purpose Interface Bus (GPIB), Hewlett-Packard Interface Bus (HP-IB), and IEEE-488 Bus, and is used worldwide.

Today, there are several other buses in addition to the GPIB that can be used for instrument control. These include: Ethernet, USB, Serial, PCI, and PXI.

Software

In addition to the hardware bus to control an instrument, software for the PC is also needed. Virtual Instrument Software Architecture, or VISA, was developed by the VME eXtensions for Instrumentation (VXI) plug and play Systems Alliance as a specification for I/O software. VISA was a step toward industry-wide software compatibility. The VISA specification defines a software standard for VXI, and for GPIB, serial, Ethernet and other interfaces. More than 35 of the largest instrumentation companies in the industry endorse VISA as the standard. The alliance created distinct frameworks by grouping the most popular operating systems, application development environments, and programming languages and defined in-depth specifications to guarantee interoperability of components within each framework.

Application development environments can support instrument control by supporting VISA. Environments supporting VISA include LabVIEW, LabWindows/CVI, MATLAB, and VEE. Furthermore the VISA library can support programming languages like C, C++, C# and others.

See also

• Instrument Driver
• Automation
• IEEE-488
• Standard Commands for Programmable Instruments
• Virtual Instrument Software Architecture (VISA)
• LabVIEW
• LabWindows
• Agilent VEE
• LAN eXtensions for Instrumentation

External links

• Instrument Control Fundamentals Presents technical content through theory, real-world examples, and interactive audiovisual tutorials - From National Instruments
• VXIplug&play
• GPIB Tutorial
• IVI Foundation
• Development Hints and Best Practices for Using Instrument Drivers - From Rohde & Schwarz